QUINCY — An 83-year-old Ludlow man was bitten on the arm and his dog killed Wednesday night when they were attacked by a pit bull as they walked the boardwalk at Wollaston Beach, state police said.

Police said the owner of the 8-year-old pit bull, a 44-year-old Quincy man, was unable to stop it from attacking because he was on rollerblades, police said.

The name of the Ludlow man was not released. He was treated at the scene for a dog bite to his arm that he suffered as he tried to pull the pit bull off his own dog, according to police.

His dog, a 10-year-old mixed breed, suffered fatal wounds in the attack and died, police said.

The Ludlow man was treated on the scene by Quincy ambulance.

According to police, witnesses said the Ludlow man was walking his dog on the boardwalk at around 6:15 p.m., and as the man on rollerblades approached with his pit bull, the pit bull attacked. The man was unable to keep the dogs separate or to stop the attack because of the rollerblades, police said. By the time police arrived, he had managed to get the pit bull under control.

The dog has since been taken into custody by the Boston Animal Control officer, and has since been transported to Quincy Animal Control. The dog, under state law, needs to be held in quarantine for 10 days for observation before it can be determined what happens to it.

The pit bull was not wearing tags on its collar, and the owner acknowledged to police that the dog was not registered with the town of Quincy, police said.

The case is being investigated by Quincy Animal Control and the Animal Rescue League of Boston.